gh-112527: Add unit test

Author: Fabian Henze

Lib/argparse.py

@@ -747,7 +747,7 @@ def _get_help_string(self, action):
             and action.default is not SUPPRESS
             and not action.required
         ):
-            defaulting_nargs = [OPTIONAL, ZERO_OR_MORE]
+            defaulting_nargs = (OPTIONAL, ZERO_OR_MORE)
             if action.option_strings or action.nargs in defaulting_nargs:
                 t = self._theme
                 default_str = _(" (default: %(default)s)")

Lib/test/test_argparse.py

@@ -5381,6 +5381,7 @@ class TestHelpArgumentDefaults(HelpTestCase):
     argument_signatures = [
         Sig('--foo', help='foo help - oh and by the way, %(default)s'),
         Sig('--bar', action='store_true', help='bar help'),
+        Sig('--required', required=True, help='some help'),
         Sig('--taz', action=argparse.BooleanOptionalAction,
             help='Whether to taz it', default=True),
         Sig('--corge', action=argparse.BooleanOptionalAction,
@@ -5394,8 +5395,8 @@ class TestHelpArgumentDefaults(HelpTestCase):
          [Sig('--baz', type=int, default=42, help='baz help')]),
     ]
     usage = '''\
-        usage: PROG [-h] [--foo FOO] [--bar] [--taz | --no-taz] [--corge | --no-corge]
-                    [--quux QUUX] [--baz BAZ]
+        usage: PROG [-h] [--foo FOO] [--bar] --required REQUIRED [--taz | --no-taz]
+                    [--corge | --no-corge] [--quux QUUX] [--baz BAZ]
                     spam [badger]
         '''
     help = usage + '''\
@@ -5410,6 +5411,7 @@ class TestHelpArgumentDefaults(HelpTestCase):
           -h, --help           show this help message and exit
           --foo FOO            foo help - oh and by the way, None
           --bar                bar help (default: False)
+          --required REQUIRED  some help
           --taz, --no-taz      Whether to taz it (default: True)
           --corge, --no-corge  Whether to corge it
           --quux QUUX          Set the quux (default: 42)